Y : a dingier colour than I

In it, he discusses such weighty topics as intellectual differences and our gregarious and slavish instincts. Obviously I'll pass on trusting this guy's interpretations (and their social consequences) but Foe points at his discussion on how numerals can be represented as colours, and it's really fascinating.

"Persons who are imaginative almost invariably think of numerals in some form of visual imagery... The pattern or 'Form' in which the numerals are seen is by no means the same in different persons, but assumes the most grotesque variety of shapes, which run in all sorts of angles, bends, curves, and zigzags..."

In Colour Associations, Galton provides anecdotal evidence for each of the figures below. For example:

"Numerals are occasionally seen in Arabic or other figures, not disposed in any particular Form, but coloured... Figs. 66, 67 illustrate the gorgeousness of the mental imagery of some favoured persons... The upper row of Fig. 69 shows the various shades of brown, ssociated with different pronunciations of the letter A..."

"The seers are invariably most minute in their description of the precise tint and hue of the colour. They are never satisfied, for instance, with saying 'blue,' but will take a great deal of trouble to express or to match the particular blue they mean... no two people agree, or hardly ever do so, as to the colour they associate with the same sound...

'When I think of Wednesday I see a kind of oval flat wash of yellow emerald green; for Tuesday, a gray sky colour; for Thursday, a brown-red irregular polygon; and a dull yellow smudge for Friday.'"

And if you're a social history of science geek, it's amazing again. Galton's theory and methodology are thoroughly explained: from the variety of human nature ("the instincts and faculties of different men and races differ in a variety of ways almost as profoundly as those of animals in different cages of the Zoological Gardens") to statistical methods ("the possibility of doing this is based on the constancy and continuity with which objects of the same species are found to vary"), composite portraiture ("the effect is to bring into evidence all the traits in which there is agreement, and to leave but a ghost of a trace of individual peculiarities") and its description, and the observed order of events ("the conditions that direct the order of the whole of the living world around us, are marked by their persistence in improving the birthright of successive generations").